Structural cracks in beams, columns & slabs

The work, step by step

General guidance based on the manufacturer data sheets. Site conditions differ: confirm the system with MCT before you start. Where we do not name a product, ask us and we will confirm the right one.

1. 1

   Step 1: Engineer's assessment

   A structural engineer must assess the cause, whether the crack is still moving, and whether repair or strengthening is needed; structural applications need an engineer's design (Sikadur-32 LP p.3). Record width, length, location and whether the crack is dry, damp or wet.

2. 2

   Step 2: Prepare the crack

   Clean the surface by high-pressure water jetting or grinding and blow dust out of the crack with compressed air (Sikadur-52 LP p.3). Fix injection ports and seal the crack face between them; Sikadur-31 DW is a non-sag epoxy for crack arris and edge sealing (Sikadur-31 DW p.1). Professionals only (p.1).

   Product for this stepAsk us

   The right product here depends on your site. We confirm it before naming it.

3. 3

   Step 3: Inject dry or damp cracks with epoxy

   Sikadur-52 LP is a low-viscosity epoxy that structurally bonds concrete sections together (Sikadur-52 LP p.1). Dry or damp cracks only, not wet; over 5 mm wide, ask us (p.2). Substrate +25 °C to +40 °C (p.2). On slabs, cracks can be gravity-filled between sealant dams; cracks through to the soffit are sealed underneath first (p.3).

   Sikadur-52 LP Sika Request a quotation

   Injection resin with good adhesion to concrete, mortar, stone, steel, and wood. (TDS p.1)

   Temperature stated in TDS

   +25 °C min. / +40 °C max (TDS p.2)

4. 4

   Step 4: Cementitious option where steel is corroding

   Sika InjectoCem-190 is a microcement grout for structural grouting of cracks that also protects corroding reinforcement (InjectoCem-190 p.1). Inject from bottom to top at 3–8 bar and pre-wet dry concrete (p.2).

   Sika InjectoCem-190 Sika Request a quotation

   Injection of Sika® Injectoflex® Systems Typ DI-1 and SikaFuko® injection hoses Filling of voids Final, rigid, cementitious sealing of cracks while simultaneously treating corroding or corrosion-prone reinforcing steel in concrete and mortar (TDS p.1)

5. 5

   Step 5: Leaking cracks take a different route

   If water is flowing through, use the leaking-cracks guide: Sika Injection-306 is an elastic injection resin for water-bearing cracks (Injection-306 p.1), for experienced professionals only.

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   The right product here depends on your site. We confirm it before naming it.

6. 6

   Step 6: Remove ports and make good

   After curing, remove the ports, grind flush and fill pockets with a fine repair mortar such as MonoTop-620, which restores edges and minor defects (MonoTop-620 p.1).

   Sika MonoTop-620 Sika

   Sika MonoTop®-620 can be applied with or withour a reinforcement matt, over concrete or mortar surfaces or over SikaTop® or Sika Monotop® mortars. It is suitable for the following uses: Use as a concrete/ mortar pore sealler or levelling mortar, Thin layer render over vertical or horizontal struc… (TDS p.1)

7. 7

   Step 7: Protect and strengthen if needed

   Coat exposed concrete as in the protective-coatings guide, e.g. crack-bridging Sikagard-550 W Elastic (G) (p.1). If the engineer finds the member needs more capacity, follow the structural-strengthening guide; the design must come from a structural engineer (SikaWrap-300 C p.3).

   Sikagard-550 W Elastic (G) Sika Request a quotation

   Sikagard®-550 W Elastic (G) is used for protection and enhancement of concrete structures (normal and lightweight concrete), especially exposed outdoor concrete surfaces with a risk of cracking. (TDS p.1)

   Temperature stated in TDS

   +8°C min. / +40°C max (TDS p.3)

Steps and product facts are taken from the manufacturer data sheets (page cited). Products are named only where the data sheet confirms the use; quantities follow a site visit or photos. General guidance: check the data sheet or ask us before you start.